Billeder på siden
PDF
ePub

II. Library Exercises and Class Discussions.

1. How do we know that the earth is spherical?

2. What relation is there between the altitude of the observer above sea level and the distance of the horizon?

3. What reason have we for thinking that the earth probably rotates on its axis?

4. What actual proofs have we of the earth's rotation.

5. In discussing the problem of the earth's revolution around the sun, what facts are to be explained?

6. What are (1) the probable reasons and (2) the actual proofs of the earth's revolution around the sun?

7. What is the "front" of the earth and when are we "in front?" Note that the "front" of a carriage is that part toward the horses.

8. How do we tell (a) latitude and (b) longitude by observation, at sea, for example?

9. What are the phenomena connected with the (a) sun's rising, (b) meridian position and (c) setting seen by a dweller at the equator throughout the year?

10. What is the sun's position at noon at the solstices and at the equinoxes to an observer at (a) the Tropic of Cancer and (b) the Arctic circle?

11. What are the phenomena connected with the sun's appearance and disappearance through the year to a dweller at the North pole?

12. Travellers go to northern Scandinavia to see the midnight sun. (a) Where are they first able to see this phenomenon, and (b) when they see it, where in the heavens is the sun located?

13. Is there any time of year when (a) the sun is on the east point of the horizon at sunrise to all places on the earth's surface, and (b) when daytime (the time of the sun's shining) is 12 hours long at all places on the earth?

14. What effect on climate would result if the earth's axis were (a) at right angles to the plane of its orbit; (b) in the plane of its orbit, and (c) inclined 45° to the plane of its orbit?

15. What planets have nearly the conditions described in a, b and c, question 14, above?

16. What becomes of the water that falls as rain?

17. What is a barometric gradient?

18. Why do some deep fresh-water lakes seldom freeze?
19. The origin, function and "death" of lakes.

*20. The facts concerning existing glaciers and the evidences of past glaciaion.

I will now give the detailed directions which have been given to the students in the case of several of the exercises already mentioned. These may serve as types of the directions which have been given for all.

Exercise. Preliminary study of a topographic map.

Apparatus Needed.-Sheets of the U. S. Geological Survey topographic maps or of the State surveys of New Jersey or Massachusetts or Connecticut. Enough maps should be provided to furnish one sheet to each pupil or group of two. Coördinate paper, ruled in inches and tenths, strips 15 inches by 4 inches. Colored pencils.

Method. The following questions are to be answered in the note book, and the profile, when completed, is to be stuck in with mucilage.

I.-1. (a) By what state or government survey and under whose direction was your map executed? (b) The name of the sheet you have and (c) what is its scale in miles per inch?

2. Find on the large map of the United States or of the state the location of the sheet you have, and make in your note book a sketch map of the state and show by lines the location of your sheet.

3. The most noticeable thing on the map is the purple or brown lines called contour lines. (a) What do they mean? At the bottom of the map notice this statement, "contour interval 20 ft." (b) What does this mean?

4. Notice (a) the crooked blue lines, (b) the black lines which are always in pairs and parallel, (c) the heavy black lines which are crossed by bars, (d) the rectangular black spots. What does each

mean?

5. Explain the meaning of each of the following arrangements of the contour lines, and give the location of a spot on the map which illustrates the arrangement; (a) close together, (b) few in

* Given in detail later.

number and far apart, (c) in circular rings, (d) parallel for considerable distances and in considerable numbers, (e) evenly spaced whether circular or parallel.

6. Find (a) the elevation of the highest spot on the map and (b) of the lowest spot. The latter can be found usually by finding where a river leaves the border of the sheet. What (c) is the difference in elevation between these two spots and (d) how far apart are they? (e) Do you think one could be seen from the other?

7. Examine the map and determine whether the other high points come near to the highest in altitude. Find the difference in altitude between several high points and the highest point, and tell how far these lower peaks are from the highest peak.

II.-8. Determine the best bicycle road between two selected places, and determine the distance by road between them. Distance and grade must both be considered in answering this question. The quality of the road cannot be told from the map. Describe briefly the route selected in your note book.

9. Connect two places by an imaginary straight line as long as your coördinate paper will allow. This line should cross some high points and, if possible, some valley. Determine upon a suitable vertical scale and construct a profile along the line between the two points. The horizontal scale here may be on the profile as on 1 mile = 1 inch, nearly. This makes the work quite You construct this profile by locating on the coördinate paper points corresponding to the elevation of the contour lines along the imaginary line connecting the two places. How many times is your vertical scale exaggerated as compared with the horizontal scale?

the map.

easy.

10. On the same piece of paper, and near the top of it, construct another profile whose vertical scale shall be 5,000 feet = 1 inch and horizontal scale as before in question 10. Compare these two profiles. The last one drawn is nearly true to nature since the vertical and horizontal scales are nearly the same. What do these two profiles tell us as to the method of showing relief in profile or on a map.

III.-11. Take your position on some high point of medium elevation and determine the limits of your vision in all directions. Describe the "view" in your note book.

12. Name all the principal rivers and lakes found on your map. 13. Find the altitude of the principal lakes and the amount of fall of the rivers. Note particularly whether your map contains the source of any large river.

[ocr errors]

14. Color brown or black the area below the contour line in the first profile you constructed (9) and write on the profile the names of the principal places passed through by the line. Indicate lakes and rivers crossed by blue. When your profile has been accepted paste it in note book.

Remarks: The aim of this exercise is to teach the student to read a topographic map and to help him to see what there is on it. Later this knowledge is made use of when we come to study topographic forms and their method of development. At a later exercise many different topographic maps will be shown the student and he will be asked to describe them, not in the minute way undertaken here, but with reference to the physiographic forms which they illustrate. There is work enough in the questions above for three laboratory exercises of two hours each. The Roman numerals may indicate about how much can be done each day. In selecting sheets those representing mountain and valley conditions of moderate relief should be chosen. The Berkshire hills and northern New Jersey furnish good subjects for study. (To be continued.)

MORGAN PARK ACADEMY,
University of Chicago, Morgan Park, Ill.

R. H. CORNISH.

GEOGRAPHICAL AIDS (II.).

VOLCANOES.

One of the phenomena of the earth concerning which there is always much said, and oftentimes badly said, in the teaching of geography is that of vulcanism, including volcanoes, earthquakes, etc. In most cases volcanoes are treated from the awe-inspiring and destructive side rather than in a common sense and rational way, in reference to their relation to each other and to the history of the country in which they are found. I well remember how, in

my earlier geographical studies, I was told that volcanoes were direct proof that the center of the earth was in a “state of igneous fusion." I had but little idea of the volcano and still less of the meaning of the words "igneous fusion."

In order that the teachers of modern geography who are readers of this JOURNAL may be helped a bit in regard to volcanic phenomena, a few suggestions regarding volcanoes and earthquakes are here presented, together with some helpful references that will give a better understanding of the features themselves. Among the questions that have to be presented to the pupil are: What is a volcano? How does it look? Where do volcanoes occur? What are some of their effects? Are there any volcanoes in the United States ? What are some of the effects of earthquakes? What relation is there between volcanic features and history, etc.? One of the best descriptions of the features of a volcano is an account of a small eruption of our typical volcano Vesuvius, and of its effects upon history as seen in Pompeii and Herculaneum, given in the book called "The Aspects of the Earth," written by N. S. Shaler and published by Scribners. Another good description, well illustrated, in which the features of Vesuvius and the Hawaian volcanoes are well brought out, is to be found in Chapters X. and XI. of Heilprin's "The Earth and Its Story," published by Silver, Burdette & Co. These chapters also give something of an idea of the life history of volcanoes, speak of their causes, their distribution and effects, and give something of the effects of earthquakes.

A very good map showing the distribution of volcanoes is to be found in Plate 27 of Tarr's "Elementary Physical Geography," published by The Macmillan Co. A smaller map, but a helpful one, is found in Werner's "Grammar School Geography." Another book which gives a good map of the distribution of volcanoes and something of the distribution of earthquakes is Mill's "Realm of Nature," page 90, published by Scribners. A statement regarding the distribution of volcanoes is given in a very readable chapter on mountains in "The Beauties of Nature" by Sir John Lubbock, published by The Macmillan Co. The following paragraph on page 244 of that book may assist those who have no access to a ready-made map:

« ForrigeFortsæt »